nonsense / meaninglessness

profound, deeply meaningful

semantics (as a field of study), semasiology

(colloquial) Clipping of 意味深長 (imishinchō).

meaningless

meaningful; suggestive; significant

historian

study of history

(Internet slang, especially anime and manga fandom) events or things from the past which one wants to whitewash/erase from history (due to it being embarrassing, poorly received, etc.); dark past

oral history